Researchers at Monash University, in Australia, have found a process to coat natural fibers such as wool, silk, and hemp that will automatically remove food, grime, and even red-wine stains by coating their fibers with titanium dioxide nanocrystals, which break down food and dirt in sunlight. Titanium dioxide is a strong photocatalyst and in the presence of ultraviolet light and water vapor, it forms hydroxyl radicals, which oxidize, or decompose, organic matter.